Dose Escalation Study of JNJ-64007957, a Humanized BCMA CD3 DuoBody® Antibody, in Participants With Relapsed or Refractory Multiple Myeloma

The study will be conducted in 2 parts: dose escalation (Part 1) and dose expansion (Part 2).
It will evaluate safety, tolerability, pharmacokinetics and preliminary antitumor activity of
JNJ-64007957 administered to adult participants with relapsed or refractory multiple myeloma.
The overall safety of the study drug will be assessed by physical examinations, Eastern
Cooperative Oncology Group performance status, laboratory tests, vital signs,
electrocardiograms, adverse event monitoring, and concomitant medication usage. Disease
evaluations will include peripheral blood and bone marrow assessments at screening (performed
within 28 days) and to confirm stringent complete response (sCR), complete response (CR), or
relapse from CR. The end of study (study completion) is defined as the last study assessment
for the last participant on study.

Inclusion Criteria:

- Documented initial diagnosis of multiple myeloma according to International Myeloma
Working Group (IMWG) diagnostic criteria

- Measurable multiple myeloma that is relapsed or refractory to established therapies
with known clinical benefit in relapsed/refractory multiple myeloma or be intolerant
of those established multiple myeloma therapies, and a candidate for JNJ-64007957
treatment in the opinion of the treating physician. Prior lines of therapy must
include a proteasome inhibitor and an immunomodulatory drug in any order during the
course of treatment. Participants who could not tolerate a proteasome inhibitor or
immunomodulatory drugs are allowed

- Eastern Cooperative Oncology Group (ECOG) Performance Status score of 0 or 1

- Women of childbearing potential and fertile men who are sexually active must agree to
use a highly effective method of contraception (less than [<] 1 percent [%] / year
failure rate) during the study and for 90 days after the last dose of study drug.
Contraception must be consistent with local regulations regarding the use of birth
control methods for participants participating in clinical trials. When a woman is of
childbearing potential the following are required: Participants must agree to practice
a highly effective method of contraception (failure rate of <1% per year when used
consistently and correctly). Examples of highly effective contraceptives for women
include user-independent methods (for example, implantable progestogen-only hormone
contraception associated with inhibition of ovulation; intrauterine device;
intrauterine hormone-releasing system; vasectomized partner) and user-dependent
methods (for example: combined [estrogen- and progestogen-containing] hormonal
contraception associated with inhibition of ovulation [oral/intravaginal/
transdermal]; progestogen-only hormone contraception associated with inhibition of
ovulation [oral/injectable]. In addition to the highly effective method of
contraception, a man who is sexually active with a woman of childbearing potential
must agree to use a barrier method of contraception (for example a condom with
spermicidal foam/gel/film/cream/suppository). Additionally, a man who is sexually
active with a woman who is pregnant must use a condom. Women and men must agree not to
donate eggs (ova, oocytes) or sperm, respectively, during the study and for 90 days
after the last dose of study drug

- Participants must sign an informed consent form (ICF) indicating that he or she
understands the purpose of and procedures required for the study and is willing to
participate in the study. Consent is to be obtained prior to the initiation of any
study-related tests or procedures that are not part of standard-of-care for the
participant's disease

Exclusion Criteria:

- Prior treatment with any therapy that is targeted to B cell maturation antigen (BCMA)
or any other CD3-redirecting drug

- Prior antitumor therapy as follows, before the first dose of study drug: Targeted
therapy, epigenetic therapy, or treatment with an investigational drug or used an
invasive investigational medical device within 21 days or at least 5 half-lives,
whichever is less; Monoclonal antibody treatment for multiple myeloma within 21 days;
Cytotoxic therapy within 21 days; Proteasome inhibitor therapy within 14 days;
Immunomodulatory agent therapy within 7 days; Radiotherapy within 21 days. However, if
the radiation portal covered less than or equal to (<=) 5% of the bone marrow reserve,
the participant is eligible irrespective of the end date of radiotherapy

- Toxicities from previous anticancer therapies should have resolved to baseline levels
or to Grade 1 or less except for alopecia or peripheral neuropathy

- Received a cumulative dose of corticosteroids equivalent to greater than or equal to
(>=) 140 milligram (mg) of prednisone within the 14-day period before the first dose
of study drug

- Known active central nervous system (CNS) involvement or exhibits clinical signs of
meningeal involvement of multiple myeloma